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From: TLC (all posts)
Date: 2001-11-16
Subject: Re: 3 Plus 1 Problem
Hi!

Don Judy wrote:
>
> The one I chose has the least serious problem, non-
> working 3 Plus 1 software. Since it would show the
> copyright notice when I SYS 1525 I figured it be a
> simple matter of swapping U25 and U26 with those of
> on the others, but the symptoms are the same.

You could as well try swapping U19, the FPLA.

If still no luck, there could be problems with some other chips in the banking logic. Though they should be harder to check/swap since they're soldered in. These are U20 (74ls139), U21 (74ls157) and U22 (74ls27).

L.

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